Carpentry Calculators

The carpentry calculators available on are online tools that you can use to simplify common construction tasks. The calculators were designed with carpenters and builders in mind, but anyone can use them. Most of the results are in decimal format, but many of them are in fraction format so that they are tape measure friendly.

Carpentry Calculators

Stair Calculator - calculate stair rise and run, stair rail angle, stringer length, and more... Check out the two versions, the automatic and manual versions.

Roof Pitch Calculator - calculate roof pitch, slope, angle and rafter length of common rafters.

Arch Calculator - calculate the focus point of an ellipse, to determine the curve of an arch. Use the results to layout and build and archway using these instructions available on

Cubic Yard Calculator - calculate volume in cubic yards and cubic feet. This calculator is useful for calculating the yards of concrete needed for a patio slab or deck footing.

Math Calculators

These math calculators add additional functionality to the construction calculators above.

Acre Calculator - converts acres to square miles, to square feet, and to square yards.  It also does the reverse for each of the four area measurements. It also provides the results in square meters and hectares. This is a handy calculator when you need to convert large areas, like lots and acreage, into different area values.

Square Root Calculator - calculates the square root of a given number and provides results in both decimal and fraction format. The fraction format makes this a useful calculator for carpentry projects.

Fraction Calculator - simply converts a decimal value to a fraction to the lowest common denominator.

If one of these calculators doesn't fit your particular need, visit carpentry math to learn about some of the formulas used in carpentry. In particular, understanding how the Pythagorean Theorem is used in calculating stairs, determining rafter pitch, and squaring walls, can be most valuable.

If you need to determine the span of a wood structural member, visit Span Tables for information on the allowable lengths of joists and rafters. The three tables available are; ceiling joist span table, floor joist span table, and rafter span table.

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